use [yourtimer invalidate]
in your code block where you're sure you get result updated. or simply change your
[NSTimer scheduledTimerWithTimeInterval: 1 target: self selector: @ selector (RefreshFFTableView) userInfo: nil repeats: YES]
to
[[NSTimer scheduledTimerWithTimeInterval: 1 target: self selector: @ selector (RefreshFFTableView) userInfo: nil repeats: NO]